Electrical measuring instrument.



A. L. R. ELLIS.

ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED ,OCT. 1. 1914.

Patented Sept; 28, 1915.

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ALVARADO L. R. ELLIS,-F LYNN, MASSACHUSETTS, ASSIG-NOR T0 GENERALELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

ELECTRICAL MEASURING INSTRUMENT.

Specification of Letters Patent.

Application filed October 1,1914. Serial No. 864,368.

To all whom it may concern:

Be it known that I, ALVARADO L. R. ELLIS, a citizen of the UnitedStates, residing at Lynn, in the county of Essex, State ofMassachusetts, have invented certain new and useful Improvements inElectrical Measuring Instruments, of which the following is a vspecification.

balance weight in its normal unrestrained My invention relates toelectrical measuring instruments, and particularly to counterbalancingdevices for such instruments.

The object of my invention is to provide a novel and improvedcounter-balancing means for the moving element of an electricalmeasuring instrument. 1

More specifically the object of my invention is to provide a novel andimproved means for properly securing the side or cross-balancing arm tothe moving elementand inexpensive construction, and furthercounter-balancing devices which may be readily and conveniently adjustedand which will securely remain in the desired adjusted positions.

. The novel features of my invention which I believe to be patentableand for which desire to secure Letters Patent are definitely indicatedin the claims appended hereto. The principle of my invention and itsapplication to the moving element of electrical measuring instrumentswill be understood from the following description taken-in connectionwith the accompanying drawings, in which: V

Figure 1 is an enlarged perspective view of the moving element of anelectrical measuring instrument of the DArsonval type embodying mypresent invention, Figs. 2

and 3 are detail views showing on an enlarged scale the construction ofthe side balancing device of my invention; Fig. 4 is an enlargedperspective view of the moving element of an electrical measuring instrument of the inclined coil type embodyingmy invention; Fig. 5 is a detailview showing the construction of the side balancing arm of the movingelement of Fig. 4; and Fig. 6 is a view of my novel helical springcountercondition.

a The moving element of an electrical measuring instrument usuallyhas'two counterbalancing devices, a side or cross balancing arm tocounterbalance inequalities in the symmetry of each side of the movingelement, and a counterbalancing device such as -a counterweight tocounterbalance for the pointer, damping, or other analogous mem-. ber ofthe movingtelement. In accordance with my present invention, the sidebalanc- Patented Sept. 28, i915.

ing arm is firmly secured to the moving element by a simple springmember in such a manner that the arm may be released for convenientadjustment by a simple movement of the spring member. The othercounterbalance device or counterweight of the moving element comprisesa. helical spring whose convolutions lie along an arc-v ual line'whenthe spring is in its normal unrestrained condition.

My invention will be best understood by reference to the accompanyingdrawings.

Fig. 1 of the drawings shows the moving element of an electricalmeasuring instrument of the DArsonv-al type. This moving elementcomprises, a frame member 10 upon which is wound a coil of Wire 11.Pivot shafts or pins 12 and13 age secured to the frame member 10, andserve to pivotally mount the-moving element in the jewels or otherbearings of the instrument in the well understood manner. A pointermember or shaft 14 extends through the shaft 18 and is rigidly securedthereto. An indicating vane 15 of a well known design is secured to oneend of the member 14;, while the other end of the member isscrew-threaded andcarries a counterbalancing device or counterweight 16.This counterweight 16 is in the form of a check or lock-nut having twosymmetrically positioned slots or saw cuts.

, The shaft 13 has a hole 17 through which a screw-threaded sidebalancing arm 18 ex tends Thehole 17 is preferably not screw- "threadedand is of slightly greater diameter tends is positioned adjacent theshaft 13. vThe apertures 20 are of greater diameter than the diameter ofthe arm 18 and are positioned near the ends of the spring 19.

Reference to Figs. 2' and 3 of the drawings v will assist inunderstanding the function and operation of the spring 19. The central5. portion of the spring bears against the shaft the arm 18 may besuitably ad uSted, and

I when the extremities of the spring are re- 20 leased they 'will moveaway from'one another and the arm .will be securely held in theapertures 20-and to the shaft 13.

Figs. 4. and 5 of the drawings show the moving element of an electricalmeasuring instrument of the inclined coil type. Va'nes 21 of the-usualtype are secured to a movable shaft 22. The shaft carries a damping disk23 of a well-known design. A pointer member is secured to the shaft 22and comprises a'bifurcated portion 24 and a single straight portion 25.A spring member 26- is secured to the shaft 22 on-one side of thebifurcated portion2$ of thepointer". This spring member has dependingcars 27 ex 5 tending on each side of the bifurcated portion 24. The earshave aperturesthrough.-

Which extends a side balancing arm 28.

' The normal. tendency ofgthe spring ears 27 is to move outwardly asviewed in Fig. 5 40 of the drawings, thus decreasing the registeringdiameters of the apertures with respect to the arm 28., By forcing, theears 27 toward each other the registering diameters of theaperthres areenlarged and the arm v e5 28 may then be freely movedthrough theapertures. The side balancing arms 18 and 28 are preferablyscrew-threaded, as indicated in thedrawings, in order to assure a betterandfir'mer engagement between the v spring member and thecounter-balancing arm, sincethe screw-threads ofi'er notches secure afirm hold. v The moving element shown. inFig. 4 is provided with 'mynovel form of. counter. -.weight 30. This counterweight comprises I I:ahelical coiled spring whose convolutions lie along an arcua l line whenthe spring is in its'normal unrestrained condition, as i n- .dicated inFig. 6' of the drawings. When the spring is placed upona straight lineelement, such as the portion 25 of the pointer, its-normal resilienttendency causes it to frictionally engage the element. The spring canbeeasily 'and'conveniently ,moved'along' be forced toward each other bya slight pressure applied by the o'p'erators thumband to which thespring member can enter to the straight element 25, but will remain inany desired position, due to its normal resilient character andtendency.

It will be observed from the foregoing description that in accordancewith the principle of my invention a flat spring holds thecounterbalancing arm in position by the inherent tendency of the springto decrease the registering diameters of the two apertures in thespring. The counterbalancing arm is positioned to extend through theapertures of the spring, and the tendency of the latter is to move theapertures out of the alinement of the counterbalancing arm, whereby thecounterbalancing arm and the '80 spring are in effect firmly claspedtogether.

'To adjust the counterbalancing arm the'normal tendency of thespringisovercome by forcing the apertures into such a position that theirregistering diameters become ap preciably larger-than the diameter ofthe counterbalancing arm whereby the arm may be moved freely through theapertures. In the examples illustrated the apertures may forefinger torelease the. clasping engagement of the spring and counterbalancing armfor the adjustment'of the latter. Thus my noveland improved constructioncom- .95 prises broadly a fiat spring-member operatively related to themoving element and to the counterbalancing arm and adapted to firmlysecure the latter to the element.

It will of'course'be understood that the illustrations are merely forthe purpose of explaining the principle of my invention. Numerouspractical embodiments of the invention in the moving element of varioustypes of electrical measuring instruments will be evident to thoseskilled in the art.

I, accordingly, do not wish to be restricted to the particularconstructions disclosedherein by way of example for the purposeofsetting forth my invention in accordance with the patent statutes. Theterms of the appended claims are, therefore, not restricted to theprecise structures disclosed but are intended to cover all changes andmodi-y- &

fications within thespirit and scope of my .7

invention. v What I claim-as new and desire to secure by Letters Patentof the United States, is

In an electrical measuring instrument the, combination with a movablemember of counterbalancing arm, and aspring member operatively' relatedto said movable member and having apertures through which-- .said armextends.

. 2.- In an electrical measuring instrument,

the combination ;with amovable member of acounterbalancing arm, and"means for se curing sa1d arm to said movable member comprising a sprmgmemberhavmg aper- 100' foregoing description and accompanying turesthrough which'said' arm extends, the registering diameters of saidapertures being adapted to be altered by varyingthe relative positionsof the apertures.

the combination with a movable member of v a counterbalancing arm, andmeans for se curing; said arm to said movable member comprising a springmember having apertures through which said arm extends, the normalresilient character of said spring member being such that said arm issecurely held in said apertures.

4. In an electrical measuring instrument,

the combination with a movable member ofacounterbalancing arm, andmeansfor securing sa1d arm tosald movable member,

comprising, a spring member having apertures of-a greater 'diameter;than thatuof said arm throu h'whi-ch said arm extends,

said arm being rmlyheld in said apertures by the normal resilientcharacter of said spring member but being adapted to be moved freelythrough saidapertures when the relative position of the apertures isvaried to increase the. effective registering diametersof said apertureswith respect to said arm.v

5. In an electrical measuring instrument,

the combination with a movable member'of a counter-balancing arm, andmeans for securing said arm to said movable member compris ng a sprlngmember mounted on said movable member and having extending ears withapertures therein through which said arm extends, ,the registeringdiameters of said apertures being adapted to be altered by varying therelative positions of the apertures.

6; In an electrical measuring instrument,

the combination with a movable shaft of a 'counterbalance comprising :ahelical coiled spring mounted on an] element operatively connected toand extending from said shaft. 5 l 7. In an electrical measuringinstrument, 3. In an electrical measuring instrument,

related to said shaf 8. In an electrical measuring instrument,

said spring being =mounted on a straight element operatively thecombination with a movable member of a counterbalancingarm, and a springele-" ment bearing against said member and exerting a force on said armto'hold said arm in an adjusted position with respect to said .member. o

.9. In an electrical measuring instrument,

the combination with a -movable member having a transverse hole thereinof a counterbalancing arm extending through said hole, and a flat springmember foperatively related to said movable member and to saidcounterbalancing arm and adapted to firmly secure said counterbalancingarm in a relatively. fixed position with respect to said,

"movable member. I

10. In an electrical measuring instrument, the combination with a movingelement of a counterbalancing arm, and a' flat spring:

member operatively related to said moving element and to saidcounterbalancing arm and adapted to'firmly secure said counterbalancingarm tosaid moving element.'

In witness whereof, I have hereunto set my hand this 28th day ofSeptember 1914 .ALVARADO L. R. ELLIS.

